Comparing peaches with apples...
I gave a herbal site a quick look-over, and found this gem:
"Three and a half ounces of cow's milk contains 118 milligrams of calcium. The same amount of hizike (a mild-flavored seaweed) contains 1400 milligrams; kelp, 1093 milligrams; and wakame, 1300 milligrams."
Now tell me, how easy is it to drink a glass of cow's milk? That's double their 3.5 ounces (100 g) right there. And then tell me, how easy is it to eat 100 g dried seaweed?
... their comparison sucks.
What would actually work, then?
Here's a quick run-down of calcium-rich foods, in mg of calcium per 100 g edible part:
hard cheeses 800-1300 mg
sardines in oil inna tin 354 mg (all those fishbones...)
parsley leaf 245 mg
raw kale 230 mg
nettle juice 190 mg
salmon inna tin 185 mg (fishbones again)
raw dandelion leaf 173 mg
boiled kale 160 mg
boiled spinach 126 mg (but the oxalic acid it also contains will use it up...)
raw leek leaf 120 mg
green olives 96 mg
fat-free milk powder 1259 mg
sesame seeds 783 mg
almonds 252 mg
hazelnut 225 mg
para nut 130 mg
sunflower seeds 100 mg
If I were to go milk-free I'd go with nettle leaf and sesame seeds. And almonds, mmmm, almonds!